Superheater



D. S. JACOBUS Aug. 1, 1933.

SUPERHEATER 2 Sheets-Sheet 1 Original Filed Feb. 17. 1922 A ATTORNEYS INVENTOR law oooooco I l I 1 II 00000 Aug? 1933- D. s. JACOBUS 1,920,198

SUPERHEATER Original Filed Feb. 17. 1922 2 Sheets-Sheet 2 Figfai Figt f 9 INVENTOR @ATTORNEYfi Patented Au 1, 1933 UNITED STATES SUPERHEATER David S. Jacobus, Montclair, N. 3., assignor to The Babcock & Wilcox Company, Bayonne,

N. J., a Corporation of New Jersey Original application February 17, 1922, Serial No.

537,153. Divided and this application April 18,

1928. Serial No. 271,057

11 Claims.

My present application is a division of my application, Serial No. 537,153, which was filed.

February 17, 1922, and relates particularly to tubes of a fluid heater which are resistant to heat.

My invention will best be understood from the following description and the annexed drawings, in which Fig. 1 is a vertical section taken on the line 1-1 of Fig. 3; Fig. 2 is a plan view of Fig. 1 showing a partial section taken on-the line 22 of Fig. 1; Fig. 3 is a section taken on the line 33 of Fig. 1, and Fig. 4 is an end view of a portion of a superheater.

Like reference characters indicate like parts in theseveral views.

In the illustrative embodiment of my invention shown in the drawings, there is a common setting 10 divided by a longitudinal wall 11 so as to form what is, in eflect; a pair of parallel flues or gas passages. In the form illustrated, the furnace chambers 12 and 13 are fired by oil burners located at the left of Fig. 1, but, if desired, the furnace chambers 12 and 13 may be formed into a single chamber by stopping 01f the portion 111 of the dividing wall 11 before it reaches the lefthand end wall of the setting.

The boiler may be of any suitable form, and as illustrated, consists of a lower water drum 14 (Fig. 1) and an upper steam and water drum 15 connected by vertical tubes 16 and divided by vertical baffies, the gases passing over the tubes 16 in a direction generally longitudinally of the drums. I

The superheater in the form illustrated is made up of two connected sections, the first section having a plurality of cross headers 20 located at the lower part of the setting and U-tubes 21 extending upwardly therefrom and arranged to connect the headers 20 serially, so that steam from the drum 15 passing through the pipe 22 will enter the header 20 at the right of Fig. 1,

and from thence will flow through the tubes 21 successively toward the left of Fig. 1. Thebafiles 23 and 24 are provided to cause the gases from the furnace chamber 12 to fiow up and down along the tubes 21. Between the furnace chamber and the tubes 21 is a high bridge wall 25 arranged to'form a vertical portion to the flue in which the superheater is located and overwhich' the gases flow before contacting with the tubes 21.

The part of the superheater which comes nearest the fire comprises a special element especial Fig. 1 by a pipe 28. The headers 26 and 27, exemplifying connections to the tubes, are connected by superheater tubes 29 of a special heatresisting material which are doubled back and forth, as shown best in Fig. 2, and which preferably are divided into series, so that the steam entering the header 26 will flow through some of these tubes to the header 2'7 and from thence through others of these tubes back to the header 26 and from thence through the remainder of the tubes back to the header 27 at a higher velocity than it flows through the tubes in the main body of the superheater, and from thence out to the point of use. This high velocity of flow and the counterfiow to the gases from the furnace chamber may be provided for by diaphragms 30 and 31 located respectively in the headers 26 and 2'7, as best shown in Fig. 4.

The dividing wall 11, in the form illustrated,

is provided with a gas exit 32 in the position shown in Fig. 1, so that the gases, after flowing over the superheater tubes 21, may pass laterally through the wall 11 into the gas pass of the boiler to jointhe gases used to heat the boiler, and pass out therewith through the exit for the boiler. ,The opening 32 may be provided with dampers by which its area may be regulated, or by which it may be closed entirely.

The form of superheater which I have illustrated is designed to give a very high degree of superheat, and for that reason, it is divided into sections, the last section being so designed and constructed that it may be subjected to the hottest gases as they pass from the furnace chamber and so that, in the event that this section is burned out, or injured, it may be readily removed and replaced without disturbing the other section of the superheater.

Moreover, as it 'is desirable to have the steam flow through this portion nearest the furnace at a very high velocity, I have provided a steam flow area through the tubes thereof which. is much smaller than the steam flow area through the tubes 21. In the particular construction illustrated, it will be seen that the steam from the header 26 flows to the header 27 through three of the superheater tubes only, whereas the steam from each of the headers 20 ilows to the next adjacent header-through many times this number of tubes. Moreover, the first pass of the steam between the headers 26 and 27 is through three tubes 29, whereas the remaining passes between the headers 26 and 27 are through two tubes only. Consequently; the steam which has been highly heated in the tubes 21 will pass velocity which in itself serves to preventthe tubes from local overheating and from on'e'of the tubes being heated to a greater extent than the others and without increasing the total frictional resistance of the flow of steam through the superheater to a prohibitive extent. The first section of the superheater thus comprises a plurality of sets of tubes, at least a portion of the tubes of one set being exposed to the radiant heat of the furnace.

The special element which comes nearest the fire is arranged so that the part of the tubes swept over by the hot gases can be readily treated to make it more resistant to deterioration at a high temperature by calorizing without treating the ends of the tubes which are expanded into the headers. The ends of the tubes which are expanded into the headers are protected from external heat and are not at as high a temperature as the parts of the tubes which are swept over by the hot gases. This is on account of the fact that the parts of the tubes swept over by the hot gases are at an intermediate temperature between that of the hot gases and the steam which is circulated through the tubes,. whereas the ends of the tubes which enter the headers, which are protected from the hot gases, are at a temperature approaching that of the steam flowing through them. Equalizing the temperature diminishes the expansive strains and makes it easier to keep the tubes from leaking where they are attached to the headers. A calorized tube cannot be expanded into a header to as great an advantage as an untreated tube, as the outer part of the tube through which the treating penetrates is of a brittle nature. It is, therefore, advantageous to make the tubes for the special element of such a form that the parts swept over by the gases can be calorized without calorizing the ends and to arrange the ends of the tubes which are left in their initial state so that they can be readily expanded, and thus protected from the hot gases. The tubes of the superheater which are subjected to the highest temperature are, therefore, composed of material differing from that of the tubes subjected to a lower temperature and better adapted to withstand high temperatures efiectively than the lower temperature tubes.

In some cases the portion 111 of the division wall 11 between the elements 12 and 13 may be omitted and when this is done, it is important that the special element be arranged so that it can be flooded with water to protect it during the starting up period when no steam is flowing through the superheater.

Water may be introduced into the special element through a valved connection 33 leading to the lower portion ot the header 2'7. The header 26 may be provided at its upper portion with a petcock 34 which will indicate, when the valve thereof is open, that the tubes of the special element have been filled with water.

In starting up the boiler and superheater when the divisional wall 11, including the portion 111, is used, the fire is lighted in the furnace chamber 13 and the hot gases pass over the boiler tubes. No fire is lighted in the furnace chamber 12 until the steam is flowing through the superheater to a sufficient amount to protect the superheater from overheating on starting the fire in the furnace chamber 12.

In starting up the boiler and superheater when the portion 111 of the dividing wall 11 is omitted, theispecial section of the superheater would be ordinarily flooded with water and the damper in the opening 32 would be closed to pre- -'vent a flow of the hot gases over the superheating surface. After steam has been generated in the boiler, the water would be blown out of the special element through a suitable drain and steam caused to circulate through the super heater. After this, the damper in the opening 32 would be opened and the hot gases allowed to flow over the superheater.

It will be obvious that the arrangement which I have described may be varied within wide limits. It will be obvious, for instance, that the two separate sections of the superheater may have, any suitable arrangement other than that illustrated, and that while the boiler with the drums extending longitudinally of the setting provides an arrangement which is compact, any 'other form of boiler may be used instead.

I claim:

1. In combination, a fluid heater comprising a chamber the walls of which are provided with openings, and tubes having their ends untreated and expanded in said openings, the remaining portions of said tubes being treated to render them resistant to deterioration, said treatment rendering the tubes difiicult to expand.

2. A superheater comprising headers and having tubes subjected to heat, the tubes being' treated where they are exposed to the heat to render them more resistant to heat, said treatment rendering the tubes 'diflicult to expand, the. ends of the tubes which are connected to the headers being untreated.

3. In combination, a furnace and a flue leading therefrom, a superheater comprising headers,

superheater tubes located in said flue and connected to said headers, the exposed portions of said tubes being treated to render them resistant to heat and the ends which enter said headers being untreated. v

I 4. In combination, a furnace and a flue leading therefrom, a superheater comprising headers, superheater tubes located in said flue and connected to said headers, the exposed portions of said tubes being calorized to render them resistant to heat, and the ends which enter said headers being untreated.

6. In combination, a furnace and a flue leading therefrom, a superheater comprising two sections, each section comprising tubes over which the gases from said furnace pass and headers to which the tubes are connected, the exposed portions of the tubes of that section over which the gases first pass being treated on their exteriors to make them resistant to heat, and the ends thereof which are connected to said headers being untreated.

7. A furnace and a flue leading therefrom to a gas outlet and a superheater in said flue, said superheater comprising headers protected from the ends thereof which are connected to said which are connected to said headers being pro--v tected from the action of the furnace gases and untreated;

9. In combination, means defining a gas pass, a connection having a tube joined thereto at one end and extending into said pass, said tube being coated with non-corrodible material within the pass but uncoated with said material where it is joined to the connection.

10. In combination, two tubes extending into a gas pass and having ends disposed outside of said pass on one side thereof, and a connection also disposed outside of said pass and joining said tube ends, said tubes being coated with noncorrodible material within the pass but uncoated where they are joined to said connection.

11. In combination, a fluid heater comprising a chamber the walls of which are provided with openings, and tubes having their ends formed of expansible material and expanded in said openings, at least the outer parts of the remaining portions of said tubes being formed of a material which is highly resistant to heat and which difiers in character from that of which the expanded ends are formed.

DAVID S. JACOBUS. 

